Monitoring the cytoskeletal EGF response in live gastric carcinoma cells

PLoS One. 2012;7(9):e45280. doi: 10.1371/journal.pone.0045280. Epub 2012 Sep 27.

Abstract

Altered cell motility is considered to be a key factor in determining tumor invasion and metastasis. Epidermal growth factor (EGF) signaling has been implicated in this process by affecting cytoskeletal organization and dynamics in multiple ways. To sort the temporal and spatial regulation of EGF-dependent cytoskeletal re-organization in relation to a cell's motile behavior time-lapse microscopy was performed on EGF-responsive gastric carcinoma-derived MKN1 cells co-expressing different fluorescently labeled cytoskeletal filaments and focal adhesion components in various combinations. The experiments showed that EGF almost instantaneously induces a considerable increase in membrane ruffling and lamellipodial activity that can be inhibited by Cetuximab EGF receptor antibodies and is not elicited in non-responsive gastric carcinoma Hs746T cells. The transient cell extensions are rich in actin but lack microtubules and keratin intermediate filaments. We show that this EGF-induced increase in membrane motility can be measured by a simple image processing routine. Microtubule plus-ends subsequently invade growing cell extensions, which start to accumulate focal complexes at the lamellipodium-lamellum junction. Such paxillin-positive complexes mature into focal adhesions by tyrosine phosphorylation and recruitment of zyxin. These adhesions then serve as nucleation sites for keratin filaments which are used to enlarge the neighboring peripheral keratin network. Focal adhesions are either disassembled or give rise to stable zyxin-rich fibrillar adhesions which disassemble in the presence of EGF to support formation of new focal adhesion sites in the cell periphery. Taken together the results serve as a basis for modeling the early cytoskeletal EGF response as a tightly coordinated and step-wise process which is relevant for the prediction of the effectiveness of anti-EGF receptor-based tumor therapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / genetics
  • Actins / metabolism
  • Antibodies, Monoclonal / pharmacology*
  • Antibodies, Monoclonal, Humanized
  • Antineoplastic Agents / pharmacology*
  • Carcinoma / drug therapy
  • Carcinoma / genetics
  • Carcinoma / pathology
  • Cell Movement / drug effects
  • Cetuximab
  • Epidermal Growth Factor / pharmacology
  • ErbB Receptors / antagonists & inhibitors*
  • ErbB Receptors / genetics
  • Focal Adhesions / drug effects*
  • Focal Adhesions / genetics
  • Focal Adhesions / ultrastructure
  • Gene Expression / drug effects
  • Humans
  • Keratins / genetics
  • Keratins / metabolism
  • Microtubules / drug effects*
  • Microtubules / genetics
  • Microtubules / ultrastructure
  • Paxillin / genetics
  • Paxillin / metabolism
  • Phosphorylation
  • Pseudopodia / drug effects*
  • Pseudopodia / genetics
  • Pseudopodia / ultrastructure
  • Signal Transduction / drug effects
  • Stomach Neoplasms / drug therapy
  • Stomach Neoplasms / genetics
  • Stomach Neoplasms / pathology
  • Time Factors
  • Time-Lapse Imaging
  • Tumor Cells, Cultured
  • Zyxin / genetics
  • Zyxin / metabolism

Substances

  • Actins
  • Antibodies, Monoclonal
  • Antibodies, Monoclonal, Humanized
  • Antineoplastic Agents
  • PXN protein, human
  • Paxillin
  • ZYX protein, human
  • Zyxin
  • Epidermal Growth Factor
  • Keratins
  • ErbB Receptors
  • Cetuximab

Grants and funding

The work was supported by grants from the German Federal Ministry of Education and Research, the Austrian Federal Ministry for Science and Research in frame of the programme “Medizinische Systembiologie – MedSys” (CANCERMOTISYS project, www.cancermotisys.eu), and the German Research Council (WI 1731 6-1, WI 1731 8-1, LE 566 18-1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.